An input and I/O self-check tests parsing, character encoding, file ownership and network failure boundaries.
Review the contracts
Review input validation, encoding boundaries, partial file I/O before answering.
Choose and explain an answer
Distinguish bytes from characters and parsing from business validation. Check partial reads, truncated output and who closes each resource.
Select an answer for every question, then check the result and read each explanation. Progress remains in this browser; this is a self-check, not a judged program submission or a credential.
Common Mistakes
A successful read can return fewer bytes than requested. Parsed input can still violate the operation's business range.